Yukio Maeda

Mechanism of Micro Chip Formation in Diamond Turning of Al-Mg Alloy

Abstract This paper deals with diamond turning experiments of Al-Mg alloy. Variation in tool setting angles using straight tools with sharp cutting edges was performed to study the difference between the machined surface roughness and the theoretical surface roughness estimated with a steady vibration model. Tears with 0.1 μm depth which are generated on the side cutting edge deteriorates the machined surface roughness. The tears are cut off by the trailing end cutting edge at a negative tool setting angle. Burrs generated at the tool setting angle less than -0.1° are another cause for the deteriorating the machined surface roughness.

A Study on Diamond Turning of Al-Mg Alloy — Generation Mechanism of Surface Machined with Worn Tool

Abstract It is well-known that the roughness of machined surfaces in diamond turning can be improved with increase of cutting length in comparison with that of the initial stage. This seems to result from an apparent increase in the wear of the diamond tool with cutting length. In this paper, the effect of diamond tool wear on surface roughness is examined for the turning of an Al-Mg alloy. The following results are obtained. (1) The tears generated on the leading end cutting edge of a straight tool deteriorate the surface roughness at a positive tool setting angle. Conversely, the tear marks decrease as the tool wear grows. (2) The surface roughness has a strong correlation with the cutting edge recession of the worn tool. (3) A residual stock removal is generated at a cutting edge recession of more than 0.3μm. Since uneven residual stock removal with tear marks is cut off by the trailing end cutting edge, the surface roughness is improved after a certain cutting length.

Improvement of Productivity in Aspherical Precision Machining with In-situ Metrology

Summary This paper deals with the development of aspherical machining technology with in-situ metrology using the stylus method for the purpose of improving machining accuracy and reducing machining time. This technique is based on the in-situ measurement of machined geometrical accuracy, which makes it possible to calculate both the deviation of nominal tool diameter from the true one and the tool setting error in tool feed and traverse directions. The machining time can be reduced to a half or one-third with application of this procedure to either aspherical grinding or diamond turning.

Development of an advanced tool-setting device for diamond turning

Summary This paper describes development of an advanced tool setting device for diamond turning. In order to machine a magnetic recording disk substrate (Al-Mg alloy) to a mirror-finished surface of less than 0.03 μm Rmax using a diamond cutting tool, a mechanism has been developed for automatic adjustment of the tool setting angle, which is a very important factor to obtain a smooth machined surface. The adjustment of the tool setting angle, which has previously been done by skilled operators, is now automated and the angular tolerance subjected to the tool replacement has been improved to an accuracy of ± 1.4 × 10−3 degrees. The machined surface roughness has also been improved to less than 0.03 μm Rmax. Moreover, the time required for the tool setting angle adjustment has been shortened to 5 minutes as compared to between 15 and 45 minutes required by the conventional manual adjustment.